CNC Machinist how-to
How to Set a Work Offset on a CNC Mill
The work offset tells the machine where the part is. Errors here scrap parts or crash machines.
The work offset tells the machine where the part is. Errors here scrap parts or crash machines. In short: secure; load; locate, then complete the remaining steps below.
Step by step
Secure the part or vise and indicate it square to the machine axes.
Load an edge finder or probe in the spindle.
Locate the X edge (or center) of the part and record the position, accounting for the edge finder radius.
Repeat for the Y axis.
Set Z using a tool setter, gauge block or probe according to shop practice.
Enter values into the correct work offset register (such as G54).
Dry-run or single-block the program with feed override low to verify.
Safety reminders for CNC machinists
- Wear safety glasses and keep loose clothing, jewelry and hair away from spindles
- Never reach into a running machine or clear chips by hand
- Keep machine doors and guards closed during operation
- Handle sharp chips and parts with gloves only when the machine is stopped
Key terms
CNC · G-code · M-code · Work offset · Tool length offset · Feeds and speeds: see the full CNC machinist glossary.